ISDN was very, very popular outside the United States. Hell, Tokyo's payphones used to have ISDN jacks for laptop users.
Tadpole later became a vendor that almost exclusively targeted the US military, but it didn't start out that way. I imagine those ISDN jacks saw a lot of use by European and Asian customers.
I went to work for a US bank in London as a sysadmin in 1994 and pretty much the first thing they did was have BT install 2x ISDN channels in my flat. It was incredible speed with what felt like almost no latency back then. What a treat! Moved to USA (also to work for that US bank) and it was like "ISD what???"
ISDN was still prevalent in commercial settings for several years. Businesses would commonly have an ISDN PRI circuit with x channels for data, y channels for voice, and z channels for BRI miscellaneous applications.
Dial-up still very much reigned supreme in the US in '97. However, we had finally stopped saddling it with punitive pricing models that discouraged people from actually taking full advantage of the Internet.
I don't remember cable modems becoming commonplace until maybe 4-5 years later. (though there was a fair bit of overlap, of course)
We had cable at our early-20s-hacker-raver-crazy-person crashpad in Edmonton, Canada in 97, 98. And DSL was available around then, too.
The year before, though, I worked in an office in Toronto with dual ISDN hookup, and it felt fast and state of the art but holy crap... looking back it certainly was not.
Telephone tarrifs were(are) state specific. At least in California for POTS, unlimited local calling had been available for a long time and wasn't too expensive. I don't think California ever got an unlimited ISDN tarrif though, which made that a very expensive proposition.
I think this is a big part of why a lot of the US got cable a bit later than other places.
Because we dropped hourly billing for ISPs and didn't really have a tradition of time-billing for local POTS calls, dial-up Internet really wasn't very expensive at all by '97.
As a result, cable-modem services were probably quite a bit more expensive than dial-up when they were new for the majority of people.
This was the era when we were still trying to convince most adults that the Internet was actually something they needed access to, so justifying the kinds of pricing we have now would likely have been impossible for all but a handful of geeks in those days.
The @Home venture got me "high speed" internet over coax in 1996, from the same company I got my cable TV from. It wasn't DOCSIS-compliant. Road Runner was a competitor at roughly the same time.
Yeah, I'm from SE Florida, so that timing sounds about right.
I recall when it was first being rolled out, it was some sort of weird hybrid service that did phone-up/cable-down. Not sure how long that nonsense lasted, because they weren't doing that anymore when my parents finally got it.
I had several iterations of this in S. Fla.--first "MediaOne" 1-way cable (downlink via a General Electric Sufboard SB-1000 ISA card with uplink via modem), then an external SB-1200 which was a combination cable modem downlink and modem uplink and an ethernet gateway. Finally, they threw all that away and gave us a DOCSIS modem.
I still remember what a pain it was to get that 1-way modem working on linux. I had to print the documentation out from Windows, and then reboot. On the other hand, learning how to get that driver[1] to compile and loaded as a kernel module was very educational.
That's the 1997 equivalent of built-in DOCSIS 3 and a coax jack on the laptop.